High energy forging press

ABSTRACT

The machine disclosed herein is known as a high velocity impact forming machine. It is provided with two tooling or anvil members and associated equipment assembled in such manner that no multiple pounding or restrike results as the machine is used. The machine has adjusting means for adjusting the energy output from stroke-to-stroke, thus enabling the user to use a sequence of varying energy forming steps such as breaking scale in hot work, preforming, and blocking. Means is provided by which the tooling is separated immediately after forming so that handling of the formed parts can commence immediately and without pause. Operation cycle time is thus used most efficiently. The structure of the machine is such that relatively low and fully controllable foundation loadings result. The machine can be provided with sufficient die area to accommodate multiple cavity tooling and is provided with means to sustain eccentric loadings from off center work. The machine is capable of stroking when the tooling and workpiece are absent without any dilatorius effects on the machine. The machine has completely adjustable tooling daylight from stroke-to-stroke.

1 Aug. 12, 1975 ABSTRACT -stroke, thus enabling the user to use a The machine disclosed herein is known as a high velocity impact forming machine. It is provided with two tooling or anvil members and associated equipment assembled in such manner that no multiple pounding or restrike results as the machine is used. The machine has adjusting means for adjusting the energy output from stroke-to sequence of varying energy forming steps such as breaking scale in hot work, preforming, and blocking. Means is provided by which the tooling is separated immediately after forming so that handling of the formed parts can commence immediately and without pause. Operation cycle time is thus used most efficiently. The structure of the machine is such that relatively low and fully controllable foundation loadings result. The machine can be provided with sufficient die area to accommodate multiple cavity tooling and is provided with means to sustain eccentric loadings from off center work. The machine is capable of stroking when the tooling and workpiece are absent without any dilatorius effects on the machine. The machine has completely adjustable tooling daylight from United States Patent 11 1 Kramer HIGH ENERGY FORGING PRESS Inventor: Kurt H. Kramer, 601 West Ave Sewaren, NJ. 07077 Aug. 10, 1971 [22] Filed:

c e D M mm 8 D00 o mN ma S D-f 9 9- m m 1d 1; ohm N m l .m p t P m A C H M 2 6 1969, abandoned.

[58] Field of Search............ 72/453, 407; 100/269 R [56] References Cited UNITED STATES PATENTS Qu 6TH uo OMM Primary E.\'aminerC. W. Lanham Assistant ExaminerGene P. Crosby PATENTED AUG 1 2l975 3, 898 834 SHEET 1 532;. INVENTOR.

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KURT H KRAMER Charles L. Lovercheck,

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SHEET 14 @MZWW HIGH ENERGY FORGING PRESS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of patent application, Ser. No. 886,130, filed Dec. 18, 1969, now abandoned.

PRIOR ART Previous machines of this type work on the counterblow principle in which anvil members are driven together by the sudden release of a high pressure gas spring. Machines in this art have a number of significant advantages over conventional mechanical and hydraulic forging presses. One is that for their size and cost, they are capable of very high forming or coining loads. Also, as with hydraulic presses, the forming load is independent of stroke, the point of maximum load may be anywhere from the beginning to the end of forming.

Tool closing velocities are in a range well above those of mechanical presses and hammers. There is evidence that many materials, especially the super-alloys, are more ductile at these higher forming velocities. That is, at higher deformation rates, these metals endure a higher percentage of deformation before fracturing. The greater forming speed is also advantageous in hot forging. The workpiece surface does not have time to cool as it moves into the die. Recrystallization heat is maintained and the metal surface does not work harden. The workpiece can be moved farther and into smaller sections with little or no draft.

Because the pressure and volumetric expansion of the gas spring can be accurately controlled, these machines are extremely repeatable. The exact same amount of energy can be delivered to workpiece after workpiece. Dimensional tolerances can be kept very tight.

The combined effects of high tonnage and velocity, and repeatability permit the forming of flash free preci sion forgings in a single closed die cavity. Considerable savings are to be had in initial billet weight and in machining after forging. In some cases heretofore unforgeable geometries can be obtained.

The previous machines of this type, however, have various undesirable features. Dies and tooling members are subjected to severe multiple pounding or restrike.

.During a stroke, the counterblow members alternately rebound from each other and impact together again under the thrust of the gas spring. For each forming, rapid pounding persists until all excess energy has dissipated. The condition is particularly bad when forming flat workpieces which create high loads. A small percentage of the energy goes into deforming the piece, while a large percentage of the energy is stored elastically in the tooling at each blow. The number of times the tooling is shock loaded is a large multiple of the number of pieces produced by the machine, and early die fatigue is invited.

This bounce or restrike is particularly distressing in hot work using liquid carried lubricants. After the first blow the carrier in contact with the hot workpiece has vaporized and blown off. During succeeding restrikes the workpiece movement is essentially unlibricated and high erosive.

Another common feature of the previous machines of this type is that after forming the dies open or separate very slowly at a rate much lower than their closing speed and generally slower than conventional hammers or mechanical presses. The anvil members are reset back to stroking position by slow-acting hydraulic pistons. This step imposes a delay in the production cycle of the machine because the operator must wait until the tooling has cleared before unloading the part.

The slow rate of tooling separation also means that in hot forming, the workpiece must be in contact with the die for periods of a second or more. Thus the die surfaces must endure an intense heating cycle after each forming, and premature heat checking results. Often parts will contract and stick to the punch before the punch clears, resulting in permanent damage to that member.

In general, previous machines of this type have been designed to forge parts solely in a single blow. Die area has been limited to that sufficient for a single die cavity. In some cases, energyoutput is fixed, the intensity of the blow cannot be varied as it can, for instance, with a steam hammer. Such common practice die-saving procedures as breaking scale, preforrning, fullering, edging, and blocking have been ruled out. The process thus far has been limited to symmetrical parts which must be completed on one blow.

High die pressures and extreme washout and erosion are inherent when deforming metal in a single blow from simple stock shapes into finishing dies of complex geometry. The logical choice of tool steels under these circumstances are those with the highest hardness and wear resistance. However, such selection has been ruled out for previous machines of this type because of the severe shock and thermal conditions they impose on tooling. Softer impact and heat check resistant steels must be used with the result that dies erode and wash out at a rapid rate making long production runs quite uneconomical.

OBJECTS OF THE INVENTION It is, accordingly, an object of the invention to provide a high velocity impact forming machine which preserves the advantages while embodying many improvements over previous machines of this type.

Another object of the invention is to provide a forming machine that is simple in construction, economical to manufacture, and simple and efficient to use.

Another object of the invention is to provide a machine which operates in a manner conducive to good die life and economical production of parts.

Another object of the invention is to providea forming machine capable of very high coining loads with relatively low and fully controllable foundation loading.

Another object of the invention is to provide a forming machine with means to separate the tooling at a very high speed immediately after each forming stroke.

Another object of the invention is to provide a machine which strikes a single blow at a time without multiple pounding or restrike.

Another object of the invention is to provide a forming machine having an especially large die area.

Another object of the invention is to provide a machine that is capable of stroking when a workpiece or the die itself is absent without self-destruction.

Another object of the invention is to provide a forming machine having a completely adjustable energy output from stroke to stroke.

Another object of the invention is to provide a forming machine having a completely adjustable stroke and completely adjustable tooling daylight from stroke to stroke.

Another object of the invention is to provide a forming machine which can perform work such as shearing,

trimming, and punching.

Another object of the invention is to provide a high velocity impact forming machine in which means is provided to accommodate reasonable eccentric forming loads without unduly stressing the machine.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of the first embodiment of the machine with a portion cross sectioned to better illustrate the invention;

FIG. 2 is a longitudinal cross sectional view of the first embodiment machine with fluid lines shown partly in schematic;

FIG. 3 is a sectional view of the primary piston chamber of the first embodiment illustrating details of construction;

FIG. 4 illustrates reset seal means used in the first embodiment machine;

FIG. 5 illustrates check valve means used in the first embodiment machine;

FIG. 6 is a sectional view of the secondary piston chamber of the first embodiment machine illustrating details of construction;

FIG. 7 shows the sequential position of the various parts of the first embodiment machine during a working cycle;

FIG. 8 shows the machine members along mathematically plotted curves relating their strokes to time for a high tonnage coining operation;

FIG. 9 is a diagram showing the relative positions of the first and second tooling members with respect to time; it is an illustration similar to FIG. 7 showing the first embodiment machine during a low tonnage deep forming stroke operation;

FIG. 10 shows mathematically plotted curves of the primary piston chamber thrust as the first tooling member strokes;

FIG. 1 l is a front view of the second embodiment of the invention with portions cross sectioned;

FIG. 12 is a side view of the second embodiment machine with portions cross sectioned to better illustrate its arrangement;

FIG. 13 is a front view of the third embodiment of the invention with portions cross sectioned to illustrate its working parts;

FIG. 14 is a cross sectional view of a fourth modification at the lower portion of the machine;

FIG. 15 is a cross sectional view of a fifth arrangement of the machine.

DETAILED DESCRIPTION OF THE DRAWINGS In this invention, the self-reaction principle of the previous counterblow type machines has been abandoned in favor of the kind of impact one sees on a pool table. One ball is propelled towards a second ball which is at rest. Upon impact, the first ball stops, while its velocity is transferred to the second ball which in turn speeds away. In this invention, the first or upper tooling member accelerates downward toward the second or lower die supporting member which is suspended at rest. Upon contact, a workpiece is forged clue to the inertia of the two impacting members. The first tooling member stops, and the second tooling member moves downward propelled by kinetic energy imparted to it during the impact. The effect is an immediate opening of the die after forming. The die opening speed is in the same range as that of the upper tooling approach speed. No pounding or restrike occurs. The punch tooling moves into the die for a single forming blow followed by immediate retreat of the lower tooling, all in an interval of milli-seconds.

The essential components of this invention are the two tool supporting members, a common frame assembly which guides these tooling members in vertical alignment, a primary piston chamber to actuate the first tooling member, and a secondary piston chamber with fluid controls to yieldably suspend the second tooling member in position for forming. Upon signal, the primary piston chamber is capable of instantaneously exerting a large gas pressure thrust, accelerating the first tooling member toward the second tooling member. This primary chamber also incorporates primary stopping means capable of exerting a counter thrust on the first tooling member if that member moves past a certain limiting point thereby stopping first tooling member motion toward the second tooling member. Reset means recompress primary pressure gas in the primary chamber means and removes the first tooling member to a position from whichit can be stroked again. The primary chamber is attached fixed to the frame assembly. The frame in turn can be anchored rigidly to a fixed foundation or fle xibly suspended by a gas spring or other means. Therefore, reaction for the first tooling member acceleration and stopping thrusts is taken either by the foundation through a stationary frame or inertially by a suspended frame.

The secondary chamber suspends the second tooling member in up position ready for forming with just sufficient force to balance the second tooling member weight. when impact propels the second tooling member downward, integral fluid controls permit the secondary piston chamber to yield and offer negligible resistance to motion until the tooling has adequately opened, after which the secondary chamber means then cushions and decelerates the second tooling member to a rapid stop. After the operator has unloaded the die and reloaded a billet, he signals the fluid controls and the secondary chamber means raises the second tooling member again to its forming position. The secondary piston chamber may itself be supported by a fixed foundation or by a suspended machine frame assembly. Therefore, reaction for stopping the second tooling member may be taken either by the foundation or inertially by a suspended machine frame.

First Embodiment Referring to FIG. 1, in the first embodiment of this invention, the frame is shown attached rigidly to the foundation. As will be seen, the primary piston chamber in this embodiment incorporates a unique primary stopping means which permits maximum kinetic energy output and absorption with minimum thrust and counterthrust reaction peaks being taken through the stationary frame to the foundation. The secondary chamber in this arrangement is shown supported directly on the foundation.

The external fluid circuitry shown in FIG. 2 aids in the discussion of the machine operations and the functions which external fluid controls must perform in conjunction with the machine. The invention is not, however. limited to the particular circuitry shown, since a variety of pump and control valve arrangements can be used to perform the necessary functions.

Referring to FIG. 3, the first embodiment primary chamber is constructed in the following manner. Shaft closure plate 11 is supported on the upper ends of side frames 80 and is clamped thereto by means of bolts 84. Closure plate 11 supports the lower ends of outer cylinder 13 and large inner cylinder 14. Small inner cylinder is received inside of large inner cylinder 14 and small cylinder 15 is supported by the upper end oflarge cylinder 14. Head closure plate 12 rests on the upper ends of outer cylinder 13 and small cylinder 15. Cylinders l3, l4, and 15 are all disposed concentric to each other and are clamped in position between closure plates 11 and 12 by means of tie rods 18 and nuts 19. Seal means 34 between cylinder 13 and lower plate 11 and seal means 35 between cylinder 13 and upper plate 12 prevent communication between the interior and exterior of outer cylinder 13.

Hydraulic cylinder 17 is supported on head closure plate 12 and is received in the counterbore as shown. Hydraulic head cap 16 rests on top of cylinder 17 and cylinder 17 is clamped in position between closure plate 12 and head cap 16 by means of tie rods 20 and nuts 21. Seal means 37 between cylinder 17 and head cap 16 prevents communication between the interior and exterior of cylinder 17.

Shaft closure plate 11 has an opening concentric to cylinder 13 which permits the primary shaft 3 of the first tooling member to reciprocate vertically in and out of the primary chamber assembly. Bushing located in this opening surrounds the primary shaft and is held in position by bolted retaining plate 26. Bushing 25 provides an appropriate wear surface for primary shaft 3 to reciprocate against. Seal means 27 prevents communication between the interior and exterior of the assembly through the shaft opening in closure plate 11. Primary piston head 4 is attached to screwing or other means to primary shaft 3. The outside diameter of piston head 4 is in sealed reciprocating contact with the bore of small inner cylinder 15. The stroke of the first tooling member and length of small cylinder 15 are disposed to insure that seal means 28 never moves out from the bore of cylinder 15.

Collar piston 6 surrounds and is in sealed reciprocating contact with primary shaft 3. The collar piston out side diameter is in sealed reciprocating contact with the lower inside wall of large inner cylinder 14. The vertical stroke of collar piston 6 is limited on top by the bottom of small inner cylinder 15 and at the bottom by shaft closure plate 11.

Fluid replenishment piston 7 is a ring shaped member which surrounds and is in sealed reciprocating contact with the outside wall of small cylinder 15. The replenishment piston outside diameter is in sealed reciprocating contact with the upper inside bore of large cylinder 14. The vertical stroke of replenishment piston 7 is limited on top by a step to greater wall diameter in cylinder 15. Piston 7 is limited at the bottom of its stroke by check seat 9.

Check seat 9 and check plate Sjust below it form an annular check valve at the bottom of small inner cylinder 15. Check seat 9 is a ring shaped member which is slotted radially outward as shown in FIG. 5 and is clamped in position between a step in the wall of cylinder l5 and a step in the bore of large cylinder 14. Check plate 8 is a plate cut in the shape of a ring and is also slotted radially outward. Check plate 8 has a very short vertical stroke between check seat 9 on top and a step in the bore of cylinder 14 below. Plate 8 and seat 9 are oriented so that if plate 8 is up against seat 9, the slots in each plate are covered by the other plate. Communication or flow upwards is self-restricting because it seats check plate 8, closing the slots. Downward communication is unrestricted because it moves plate 8 down from seat 9, opening the slots. Slotting after this fashion gives the check valve a large orifice with a very short opening stroke.

Head closure plate 12 has an opening concentric to outer cylinder 13 through which opposed reset piston 5 reciprocates. Bushing 22 is located in this opening and surrounds opposed piston 5. This bushing provides an appropriate wear surface for opposed piton 5 piston reciprocate against. Bushing 22 is clamped in place by hydraulic cylinder 17. Seal means 33 prevents communication around the opposed reset piston between, above and below bushing 22. Seal means 38 prevents communication between the interior and exterior of cylinder 17 and seal means 39 prevents communication to the exterior of the chamber between bushing 22 and closure plate 12. The upper end of the opposed reset piston is flanged intermittently about its diameter. This flange is in reciprocating contact with the bore of cylinder 17. The opposed piston can travel downward until its upper flange contacts bushing 22. The opposed piston can travel upward until it contacts hydraulic head cap 16. Hydraulic cylinder 17 and head cap 16 comprise a hydraulic actuation chamber for opposed reset piston 5.

Face flange 23 is attached by screwing or other means to the lower end of opposed piston 5. Face flange 23 carries a radial reset seal ring 10 of resilient composition and is designed to sealingly enter into engagement with the upper face of primary piston head 4. Pressure control sleeve 24 fits in an eccentrically located hole through primary piston head 4. In sealed engagement with the primary piston head and primary piston shaft, sleeve 24 provides pressure communication between the upper face of the piston head and drillings in the first tooling member which lead to hose connection 44 and external depressurization and stroke control valves. Sleeve 24 also locks primary piston head 4 from unscrewing from the primary shaft.

Diameter N of primary shaft 3 is less than diameter P of opposed piston 5. Diameter R of primary piston head 4 is greater than diameter 0 of face flange 23. The outside diameter of collar piston 6 is greater than diameter R.

Region A is confined between closure plates 11 and 12. Region A communicates around primary piston shaft 3 below collar piston 6 and through porting slots at the bottom of inner cylinder 14 into the annular space between cylinders 14 and 13 and through porting slots at the top of small inner cylinder 15 into the space above primary piston head 4 and below and around the portion of the opposed piston 5 exposed below head closure plate 12. Region A confines the primary pressure gas which is compressed by the reset system to store energy and released by stroke initiation means to impart that energy in first tooling member stroking motion. A constant quantity of primary pressure gas is maintained in region A by means of valve V12.

Intermediate region C is confined by the lower end of primary piston head 4, collar piston 6, the under surface of check valve plates 8 and 9, the lower bore portion of large inner cylinder 14 and the inside wall of small inner cylinger 15. intermediate region C is filled with hydraulic fluid which functions in the stopping and limiting of first tooling member stroking motion. Two spigots 42 provide communication between intermediate region C and the external hydraulic circuit. Region D is confined by the upper surface of check valve plates 8 and 9, the upper bore portion of inner cylinder 14, the outer surface of small cylinder 15, and the underface of replenishment piston 7. Region D is also filled with hydraulic fluid. The total volume of hydraulic fluid in intermediate region C and replenishment region D is left constant during operation; filling and bleeding the regions is accomplished by valves V9 and V10. The upper face of collar piston 6 is recessed CC for hydraulically cushioned engagement with primary piston head 1, when the first tooling member down stroke is being stopped; intermediate region C fluid acts as the cushioning medium when the two members enter malefemale engagement.

Region F is confined by the upper end of cylinder 15, the upper bore portion of cylinder 14 and the top of fluid replenishment piston 7. Seal means 36 between inner cylinders 14 and 15 prevents communication with region A primary pressure gas. Drilled holes and piping 46 communicate region F with external fill and bleed valves 15 and 16. A fixed quantity of pressure gas is maintained in region F during operation, the pressure being limited to approximately one fourth that of the primary pressure gas confined in region A.

Region E is the hydraulic chamber confined by opposed piston 5, cylinder 17, bushing 22 and head cap 16. It is filled with hydraulic fluid and communicates with the external hydraulic power system through porting means 41 in head cap 16.

The secondary piston chamber shown in FIG. 6 is arranged surrounded by an annular accumulator fluid control means. Chamber closure plate 56 rests on and is suitably anchored to the foundation. The lower-ends of outer and inner accumulator cylinders 59 and 58 and chamber cylinder 57 rest on closure plate 56. Upper plate 55 rests on the upper ends of outer cylinder 59 and inner cylinder 58. Upper plate 55 has an opening through which chamber cylinder 57 extends upward. Upper plate 55 rests on a step in the outer wall of chamber cylinder 57. Accumulator cylinders 58 and 59 and chamber cylinder 57 are all disposed concentric to each other and are clamped in position between upper plate 55 and closure plate 56 by tie rods 70 and nuts 71. Seal means 65 and 66 prevent communication between the interior and exterior of cylinder 59. Seal means 68 and 69 prevent communication between the interior and exterior of cylinder 58. Seal means 67 prevents communication between the interior and exterior of the assembly at the opening in upper plate 55. A circular recess in closure plate 56 receives the lower end of chamber cylinder 57 in fitted engagement, restricting communication between the inside and outside of cylinder 57 at its lower end.

The upper end of chamber cylinder 57 has an entrance through which secondary piston 50 is permitted vertical reciprocating motion in and out of the assembly. Bushing 60 located in this entrance surrounds piston 50 and is held in place by bolted retaining plate 61.

Bushing 60 provides an appropriate wear surface for piston 50 to reciprocate against. Seal means 62 prevents communication with the exterior of the chamber through the piston entrance. As shown, piston 50 is flanged 51 at its interior end. Piston 50 can stroke upwards until its flange 51 contacts the piston entrance and stroke downward until it contacts check plate 54 resting on closure plate 56.

Check plate 54 covers a drilled port in closure plate 56. Plate 54 is free to lift, permitting free discharge from the port. Communication into the port restricts itself by seating the check plate over the port.

Accumulator piston 52 is a ring shaped member in sealed reciprocating contact with the outside wall of accumulator cylinder 58 and the inside wall of cylinder 59. A step in the wall of cylinder 58 limits the upward travel of accumulator piston 52 while the piston can move down until it contacts check plate 53. The maximum displacement (area multiplied by stroke) of accumulator piston 52 equals the maximum displacement of secondary piston 50.

Check plate 53 is part of the fluid control arrangement and is cut in the shape of a ring. lt seats on closure plate 56 just below accumulator piston 52. Check plate 53 covers ports drilled in a circle in plate 56, permitting free flow out of these ports and restricted flow into these ports.

Piston region G is confined within chamber cylinder 57 and surrounds secondary piston 50 within cylinder 57. Piston region G communicates through ports in the wall of cylinder 57 with the annular space between chamber cylinder 57 and accumulator cylinder 58. From this space, piston region G communicates through inter-drilled holes in plate 56 with the port openings under control check plate 53. Piston region G also communicates through external piping to check valve V22. Piston region G is filled with hydraulic fluid.

The bore of chamber cylinder 57 is relieved on its upper portion to a diameter greater than diameter U of the secondary piston flange. This permits unrestricted flow of piston region hydraulic fluid above and below the secondary piston flange. Just below the wall ports, the bore of cylinder 57 decreases in diameter to a fitted female engagement with the male secondary piston flange, forming secondary stopping cushion means GG at the lower end of the secondary piston travel.

Accumulator region H is confined between accumulator cylinders 58 and 59 below accumulator piston 52 and above control check plate 53. Region H also communicates through a drilled hole in check plate 53 and a passage in closure plate 56 with external bi-pass control valve V17. Accumulator region H is filled with hydraulic fluid.

Region J is confined in external piping and a drilled passage in plate 56 between valves V17, V20, and V22 and the port opening under check plate 54. Region J is filled with hydraulic fluid. Region L is confined in the external hydraulic circuit between valves V23, V24, V20, and V2].

Valves V24 and V23 fill and bleed regions G, H, J, and L from-the main hydraulic circuit. Once set, the total volume of fluid of the four regions does not charge during operation of the machine.

Region K is confined between inner and outer accumulator cylinders 58 and 59 below upper plate 55 and above accumulator piston 52. Valves V25 and V26 fill and bleed region K with accumulator pressure gas,

pressurizing the accumulator fluid control system. Once set, the quantity of accumulator pressure gas in region K remains constant during machine operation.

Second tooling member 2 resets on and is supported by the upper end of secondary piston 50. First tooling member 1, the primary piston chamber, the second tooling member 2, and the secondary piston chamber assembly are all disposed centered along a common axis.

The underface of the first tooling member is fitted with tapped holes, T-slots or other means for attachment of the upper halves of forming dies. The upper face of the second tooling member is fitted in similar manner with means for attaching the lower halves of forging tooling. Hydraulic piston 93 located in a bored hole in the upper face of second tooling member 2 provides means for ejecting formed parts from the lower tooling. Similar means can be provided in the first tooling member for stripping parts from the upper tooling.

FIG. 7 shows the forming cycle of the first embodiment machine in five steps. Step I shows the machine in the stroke position. Steps II, III, and IV show the rapid succession of forming, stopping of the first tooling member, and stopping of the second tooling member. Step V shows the machine reloaded and the primary pressure gas reset preparatory for another stroke.

STEP I Ready to Stroke First tooling member 1 is held at stroke position in the following way: gas region B is temporarily confined between the engaged faces of primary piston head 4 and face flange 23 attached to the lower end of opposed reset piston 5. Reset seal 10 carried on the out side diameter of face flange 23 isolates region B from primary pressure gas of region A. Region B, connected to external control means through sleeve 24 and passages in the first tooling member, is at this step depressurized and vented to atmosphere by the external con trol. The pressure of region A acts down on face flange 23 clamping opposed piston 5 to the primary piston head.

Primary pressure in Region A is transmitted by collar piston 6 to fluid in intermediate region C. Since diameter P is greater than diameter N, the area of primary region A pressure acting down on top of the primary piston head is less than the under head area acted upon by equal pressure in intermediate region C. Thus a net upward thrust is acting on the clamped together primary and opposed pistons, and they press up against the hydraulic fluid which at this step is trapped in hydraulic actuation chamber E.

The second tooling member is held at forming position in the following way: The weight of-the second tooling member presses down through secondary piston 50 on the hydraulic fluid in piston region G, creating a certain pressure. This pressure communicates through the inter-drilling past control check plate 53 to accumulator region H below accumulator piston 52. Accumulator pressure gas in region K above piston 52 is set at a slightly higher pressure than the weight induced pressure in piston region G. At this step the dead weight of the second tooling member is not sufficient to displace fluid from piston region G and lift accumulator piston 52 against pressure gas in region K.

STEP II Stroke Initiation and Forming The primary pressure gas is released to urge the first tooling member in a downward stroke in the following way: Stroke initiation valve V11 closes temporary region B off from atmosphere and connects region B to the primary pressure gas of region A. Primary pressure gas enters region B and now acts down on the entire face area of primary piston head 4. The first tooling member moves down, separating away from opposed piston 5. Once radial seal ring 10 has cleared engagement wall 47 on the upper face of piston head 4, primary pressure gas flows directly over the top of piston head 4 thrusting the first tooling member downward. In so doing, the primary pressure gas expands, releasing its energy to the first tooling member.

Region C intermediate fluid moves down preceding piston head 4 and causing collar piston 6 to displace downward at a proportionally slower speed than that of the first tooling member.

Forming occurs in the following way: At some point in stroke the upper tooling contacts the work piece resting in the lower die. The work piece deforms and the resulting forging force acts upwards decelerating first tooling member 1 and acts downward, accelerating second tooling member 2. When the first tooling member has decelerated and the second tooling member has accelerated to an equal velocity, metal deformation ceases.

While metal deformation is occuring, the inertial forging force acting downward on the second tooling member far exceeds the upward acting force exerted by secondary piston 50, because the piston force depends on fluid pressure sustained in piston region G by the annular control accumulator and by the accumulator pressure gas of region K. The secondary piston yields to the overbalance of forces during forming and permits the second tooling member to accelerate and move downward. Simultaneously, hydraulic fluid is displaced from piston region G into accumulator region H and accumulator piston 52 yields and moves in an upward direction.

STEP III Stopping of First Tooling Member and Tooling Separation After forming, the first tooling member may have residual downward velocity. It may be traveling at the same velocity as the second tooling member with the upper and lower tooling stuck together. Or if the forging is shallow and the forming tonnage high, elastic energy stored in the tooling during impact springs the tooling members apart after forming, further slowing the first tooling member while giving an additional velocity boost to the second tooling member.

Primary stopping of the first tooling member occurs after forming in the following way: At some limiting point in mid-stroke, primary piston head 4 engages collar piston 6. If the first tooling member travels below this point, it pushes collar piston 6 with it, expanding the volume of intermediate region C. When this happens, the low gas pressure of region F moves fluid replenishment piston 7 downward, pushing fluid from region D past check plate 8 to replenish fluid in intermediate region C as the collar piston recedes downward. Primary pressure of region A, acting upward on the collar piston against the low replenishment pressure acting down in region C, creates a net upward thrust which decelerates the collar piston and the first tooling member with it. 

1. A forming machine comprising in combination, a first tooling member, a second tooling member, a common frame, said first and second tooling members being adapted to reciprocate along a common axis on said machine, said first and second tooling members provided with means for attaching forming dies to their adjacent surfaces, primary piston chamber means arranged together with said first tooling member confining primary pressure gas which through expansion is adapted to urge said first tooling member in direction toward said second tooling member, primary stopping means limiting expansion of said primary pressure gas and limiting distance of travel of said first tooling member in direction toward said second tooling member without disabling said machine wherby an end of stroke position for said first tooling member and a corresponding normal expanded condition of said primary pressure gas are determined independently of second tooling member motion or position, reset means adapted to compress said primary pressure gas from said normal expanded condition and cause said first tooling member to move from said end of stroke position in direction away from said second tooling member to a beginning stroke position, stroke initiating means adapted to release said primary pressure gas from said compressed condition and said first tooling member from said beginning stroke position whereby said primary pressure gas propels said first tooling member against said primary stopping means and said primary stopping means operates to limit rest position and whereby said first tooling member is actuated to strike a forming blow against said second tooling member positioned for forming, secondary piston chamber means arranged in association with said second tooling member, fluid control means adapted to regulate fluid in said secondary piston chamber means whereby said secondary piston chamber means is caused only in response to operator controlled signal to move said second tooling member along said common axis in direction toward said first tooling member to forming position and whereby said secondary piston chamber means is caused to maintain said second tooling member at said forming position, said fluid control means adapted to allow said secondary piston chamber means to yield to said induced second tooling member motion and sustain said motion after a single forming blow while first tooliing member motion is being curtailed by said primary stopping means whereby said second tooling member is caused to separate completely away from said first tooling member after a single forming blow, secondary stopping means limiting the distance said second tooling member may travel in direction away from said first tooling member after a single forming blow without disabling said machine.
 2. The forming machine recited in claim 1 wherein said primary piston chamber means having respectively at its opposite ends shaft closure means and head closure means, primary piston means having sealed reciprocating entry to within said primary chamber means through said shaft closure means, said reset means comprising opposed piston meanS having sealed reciprocating communication to within said primary chamber means from head closure means and situated in opposed relation to said primary piston means within said primary chamber means, the interior ends of said opposed piston and primary piston means disposed facing each other, said primary pressure gas confined in said primary chamber means communicable with the interior ends of opposed piston means and primary piston means, said reset means comprising hydraulic actuation means adapted to urge said oppose piston means into said primary chamber means toward said primary piston means while said first tooling member is at limiting rest position whereby primary pressure gas is compressed from its normal expanded condition until the interior end face of said opposed piston means engages the interior end face of primary piston, said rest means comprising depressurizing means adapted to reduce the gas pressure between said engaged piston faces, seal means cooperating to isolate said depressurized piston faces from primary pressure gas whereby the net thrusts on primary piston and opposed piston are altered in such manner that upon release of said hydraulic actuation means said piston means remain engaged and move together and said primary piston means retracts into said primary chamber means and thereby moves said first tooling member from limiting rest position in direction away from said second tooling member until stopped at any stroke position by locking said hydraulic actuation means, said stroke initiation means operating upon signal to increase pressure on said engaged piston faces and thereby urge primary piston means to disengage from opposed piston means and disengage seal means whereby primary pressure gas is released to the full end face of said primary piston producing a sudden thrust urging primary piston outward from said primary chamber means and whereby through expansion of primary pressure gas said first tooling member is urged from stroking position in direction toward said second tooling member.
 3. The forming machine recited in claim 1 wherein secondary piston shaft means adapted for sealed reciprocating motion into and out from said secondary chamber means through piston entrance means, secondary piston head means in rigid attachment to said secondary piston shaft means within said secondary chamber means and disposed in sealed reciprocating contact within chamber cylinder means, said secondary piston head means having greater diameter than said secondary piston shaft means, secondary pressure gas confined in said secondary chamber means and disposed communicable within said chamber cylinder means and around said secondary piston shaft means between the underhead surface of said secondary piston head means and said piston entrance means whereby, when a single forming blow induces second tooling member motion in direction away from said first tooling member, said secondary piston shaft means is released to the thrust of said secondary pressure gas which acting on the underhead surface of said secondary piston head means urges secondary piston shaft means to move into said secondary chamber means and thereby causes second tooling member motion following a single forming blow to continue and be sustained until said second tooling member has adequately separated away from said first tooling member.
 4. The forming machine recited in claim 1 wherein said first tooling member disposed vertically above said second tooling member, said first and second tooling members adapted for reciprocating motion along a common vertical axis, said primary piston chamber means embodying closure means rigidly connected to said common frame.
 5. The forming machine recited in claim 4 wherein said common frame is supported with respect to a fixed foundation by flexible spring means.
 6. The forming machine recited in claim 5 wherein said flexible spring means constituting expansible gas cushion chambers, said gas cushiOn chambers being supported to said fixed foundation by hydraulic piston chamber means whereby the vertical position of said common frame is hydraulically adjustable without necessity of varying the quantity of gas in cushion chambers.
 7. The forming machine recited in claim 1 wherein said primary piston chamber means having respectively at its opposite ends shaft closure means and head closure means, primary piston shaft means aligned in the direction of said common axis and having sealed reciprocating entry to within said primary chamber means through shaft closure means, primary piston head means rigidly connected to said primary shaft means within said primary chamber means, said primary chamber means having inner cylinder means, said primary piston head means disposed in sealed reciprocating contact with the inside wall of inner cylinder means, said primary pressure gas being confined within said primary chamber means outside and surrounding said inner cylinder means and communicable to within said inner cylinder means through porting means at head closure means whereby primary pressure gas is capable of exerting a force on said primary piston head means and by expansion capable of urging said primary piston shaft out from said primary chamber means whereby said first tooling member is urged from stroke position in direction toward said second tooling member.
 8. The forming machine recited in claim 7 wherein said inner cylinder means constituting a small inner cylinder and a large inner cylinder, small cylinder having a smaller inside diameter than large cylinder, small inner cylinder arranged aligned with and connected to large inner cylinder with said large cylinder disposed toward the shaft closure end of said primary chamber means, small inner cylinder means disposed toward said head closure end, primary piston head disposed in sealed reciprocating contact within small inner cylinder means, said primary stopping means constituting collar piston means disposed within large inner cylinder surrounding and in sealed reciprocating contact with primary piston shaft between shaft closure means and the underhead surface of primary piston head means, collar piston disposed at its outer diameter in sealed reciprocating contact with large inner cylinder means, said collar piston means having greater face area than primary piston head, an intermediate region confined within said large and small inner cylinder means surrounding primary piston shaft means between the underhead surface of piston head and collar piston means, intermediate region sealingly isolated from primary pressure gas and adapted to be filled with hydraulic fluid, said primary pressure gas confined outside said large and small inner cylinder means and directed to witin small inner cylinder through porting means at said head closure means and directed to within large inner cylinder means through porting means at shaft closure means and thereby directed to exert a force on collar piston means whereby hydraulic fluid in intermediate region is pressurized when said first tooling member is propelled from stroke position toward said second tooling member and whereby outward motion of primary piston shaft means from said primary chamber means is resisted by a nominal force of said fluid pressure in intermediate region acting on said underhead surface of primary piston head until said collar piston means engages said underhead surface and begins moving with primary piston head whereby intermediate region commences expanding in volume and thus loses fluid pressure and the force resisting said outward motion of primary shaft suddenly increases to the force of primary pressure gas acting on the full face of collar piston means whose face area is greater than the full face area of primary piston head and whereby the resulting net force resists and stops further outward motion of primary piston shaft from said primary chamber means and causes said first tooling member together with Piston shaft and collar piston means to move to a limiting rest position at which said fluid in intermediate region is again pressurized by primary pressure gas in its most expanded condition acting on collar piston and at which collar piston means remains engaged with primary piston head.
 9. The forming machine recited in claim 8 wherein replenishment means adapted to keep intermediate region completely occupied and supplied with low pressure fluid when intermediate region expands following engagement of collar piston with primary piston head during outward movement of said primary piston shaft means, check valve means preventing replenishment fluid supplied into intermediate region during its expansion from flowing back out of said intermediate region faster than at a restricted rate whereby once stopped after a forming blow primary piston shaft and collar piston return with controlled speed inward into said primary chamber means until reaching limiting rest position at which position intermediate region has its original volume, primary piston head means and collar piston means arranged to have close clearance male-female engagement whereby intermediate region fluid is trapped between said members during engagement and thereby provides hydraulic cushioning which prevents damage to said two members.
 10. The forming machine recited in claim 1 wherein said primary piston chamber means having respectively at its opposite ends shaft closure means and head closure means, primary piston means having sealed reciprocating entry to within said primary chamber means through said shaft closure means, said reset means comprising inner piston means adapted to reciprocate within said primary chamber means in a common direction with primary piston means between the interior end of said primary piston means and head closure means, an inner piston region confined between inner piston means and said primary piston means, said primary pressure gas confined within said primary chamber means and disposed communicably with the face of inner piston means adjacent to head closure means, said primary pressure gas isolated from inner piston region, said reset means comprising hydraulic power means adapted to supply fluid into said inner piston region and thereby displace inner piston away from primary piston while said first tooling member is at limiting rest position and thereby compress said primary pressure gas from its normal expanded condition until inner piston means engages head closure surface, said reset means comprising depressurizing means adapted to reduce the gas pressure between the engaged surfaces of inner piston and head closure with seal means cooperating to isolate said depressurized surfaces from said primary pressure gas whereby the net thrusts on inner piston means and said primary piston means are altered in such manner that upon release of said fluid from inner piston region, said inner piston means remains engaged with head closure while primary piston means retracts into said primary chamber means thereby causing said first tooling member to move from limiting rest position in direction away from said second tooling member until stopped at any stroke position by locking any remaining fluid in innner piston region, said stroke initiation means operating upon signal to increase pressure on said engaged piston and closure surfaces thereby urging inner piston means away from the surface of closure means disengaging seal means whereby said primary pressure gas is released to act on the face of inner piston producing a sudden thrust urging said inner piston together with remaining fluid in inner piston region and said primary piston to move together and propelling said primary piston means outward from said primary chamber means whereby said primary pressure gas expands and said first tooling member moves from stroke position in direction toward said second tooling member.
 11. The forming machine recited in claim 10 wherein Said seal means comprises a ring shaped member of resilient composition carried in a groove around the cylindrical outside wall of said inner piston means and disposed adjacent the end of said inner piston means which engages said head closure surface whereby during said engagement said seal means is held sealingly against a mating cylindrical engagement wall set in said head closure surface whereby said seal means and cooperating engagement wall form a surrounding boundary which isolates the engaged surfaces of said inner piston and head closure from communication with primary pressure gas.
 12. The forming machine recited in claim 10 wherein said primary piston chamber means being constructed with cylinder means, primary piston head means in rigid attachment to primary piston shaft means within said primary chamber means and disposed in sealed reciprocating contact with the inside wall of said cylinder means, said inner piston means also disposed in sealed reciprocatinng contact with the inside surface of said chamber cylinder means, said inner piston region confined in said cylinder between primary piston head and inner piston means, said inner piston region communicable with external hydraulic power and control means through delivery tube means attached to head closure means and extended into said primary chamber means passing sealingly through said reciprocating inner piston to within inner piston region.
 13. The forming machine recited in claim 12 wherein said primary piston head having greater outside diameter than said primary piston shaft means, said primary stopping means constituting a gas cusion region confined in said chamber cylinder means surrounding said primary piston shaft means between said shaft closure means and the underhead surface of said primary piston head means and isolated from communication with said primary pressure gas whereby outward stroking motion of siad primary shaft means from said primary chamber means causes compression of said gas cushion region and pressure buildup on said underhead surface of primary piston head means and through said pressure buildup limiting said outward motion and preventing disabling impact between said shaft closure means and said primary piston head and whereby first tooling member motion from stroke position is terminated at a limiting rest position in which the thrusts exerted on said primary piston head means and inner piston means by said primary pressure gas and said gas cushion are in equilibrium, said reset means dependent upon said gas cushion whereby upon depressurization of the engaged surfaces of inner piston and head closure the thrust of said primary pressure gas acting axially on said inner piston means is reduced to less than the force of said gas cushion acting on the underhead surface of primary piston head means and whereby upon release of said hydraulic fluid from said inner piston region said thrust difference holds inner piston means engaged against head closure means and causes said primary piston means to retract into said primary camber means thereby moving said first tooling member from limiting rest position to stroke position.
 14. The forming machine recited in claim 1 wherein said secondary chamber means having chamber closure means at one end and a piston entrance at its other end, secondary piston means adapted for sealed reciprocating motion into and out from said secondary chamber means through said piston entrance, a piston region confined within said secondary chamber means by the interior end of secondary piston means, said fluid control means adapted to deliver hydraulic fluid into said piston region only in response to operator controlled signal whereby said secondary piston means is moved out from said secondary chamber means and whereby said second tooling member is moved in direction toward said first tooling member to forming position, said fluid control means adapted to maintain hydraulic fluid in said piston region wherEby said secondary piston means is held in position extended from said secondary chamber means and whereby said second tooling member is maintained at forming position until said first tooling member strikes a single forming blow against said second tooling member thereby imparting motion to said second tooling member in direction away from said first tooling member and inducing a hydraulic pressure buildup in said piston region, said fluid control means adapted to yield to said pressure buildup and thereby permit said secondary piston means to displace hydraulic fluid in piston region and to move into said secondary chamber means whereby said motion imparted to said second tooling member is sustained following a single forming blow.
 15. The forming machine recited in claim 14 wherein said secondary stopping means operating after a forming blow at the end of secondary piston means travel into said secondary chamber means through close clearance male-female engagement between said secondary piston and the interior surface of said secondary chamber means whereby piston region hydraulic fluid metering from between piston and chamber closure creates a pressure force to stop the motion of secondary piston and said second tooling member and whereby said fluid acts as a cushioning medium to prevent damage to said piston and chamber closure means.
 16. The forming machine recited in claim 14 wherein said fluid control means comprising valve piston means disposed aligned with and facing said secondary piston means within said secondary chamber means, valve piston adapted for reciprocating motion between said chamber closure means and an annular valve seat surface in the interior wall of said secondary chamber, said secondary stopping means adapted to operate after a forming blow at the end of secondary piston''s travel into said secondary chamber means through close clearance male-female engagement between said secondary piston means and valve piston means whereby piston region hydraulic fluid metering from between said secondary and valve piston means creates a pressure force to stop the motion of secondary piston and said second tooling member and whereby said piston region fluid acts as a cushioning medium to prevent damage to said secondary piston and valve piston means.
 17. The forming machine recited in claim 14 wherein said fluid control means comprising valve piston means having a valve face communicable with hydraulic fluid in said piston region, said valve piston means disposed having reciprocating motion enabling said valve face to move against an annular valve seat surface in the interior wall of said secondary chamber means and adapted thereby to isolate said piston region from a low pressure reservoir arranged with said secondary chamber means, valve spring means adapted to urge said valve piston means toward said valve seat surface whereby said valve piston means is held seated at all times against the force of piston region hydraulic pressure acting on said valve face except while said hydraulic pressure in said piston region over-balances the force of said valve spring, and whereby said valve piston means when seated contains said fluid in said piston region from flowing into said low pressure reservoir and thereby maintains said second tooling member at forming position until a forming blow and whereby second tooling member motion induced by a forming blow continues and is sustained as long as secondary piston displacement into said piston region produces sufficient hydraulic pressure to hold said valve piston means unseated or until said secondary stopping means halts said motion.
 18. The forming machine recited in claim 14 wherein said fluid control means comprising gas pressurized hydraulic accumulator means, communication between said accumulator hydraulic fluid and fluid in piston region of said secondary chamber being controlled by check valve means and separately by bypass valve means, said check valvE means disposed to permit fluid flow from said piston region into said accumulator means while preventing reverse flow from said accumulator means into said piston region, said bypass valve adapted to open only in response to operator controlled signal and thereby deliver pressurized accumulator fluid into piston region, moving secondary piston means out from said secondary chamber means and said second tooling member to forming position whereupon said bypass valve is adapted to reclose, said accumulator means adapted to yield and receive fluid through said check valve means from said piston region when a forming blow induces a pressure buildup in said piston region exceeding said accumulator gas pressure, whereby said secondary piston means is permitted to move into said secondary chamber means displacing fluid and second tooling member motion is thereby sustained following a forming blow.
 19. The forming machine recited in claim 18 wherein said accumulator means integrally arranged in said secondary chamber means comprising annular piston means disposed having sealed reciprocating motion in an annular space isolated within said chamber means surrounding piston region, said accumulator piston means disposed sealingly segregating said accumulator pressure gas from accumulator hydraulic fluid within said annular space, said check valve means comprising annular check plate means disposed with seating motion over port means which open from said piston region into said accumulator hydraulic region whereby flow from said accumulator region into said ports causes said check plate to seat and cover said ports thereby rendering said flow self-restrictive and whereas flow out from said ports into accumulator region causes said check plate to unseat and open passage for said fluid.
 20. The forming machine recited in claim 18 wherein said check valve means comprising valve piston means having a valve face communicable with hydraulic fluid in said piston region, said valve piston means disposed having reciprocating motion enabling said valve face to move against an annular valve seat surface in the interior wall of said secondary chamber means, said accumulator means integrally arranged in said secondary chamber means and comprising annular shaped accumulator piston means communicable with hydraulic fluid in an accumulator region which surrounds said piston region, said accumulator piston means disposed surrounding and in sealed reciprocating contact with said valve piston means, said valve piston means and said accumulator piston means together confining and being together acted upon by accumulator pressure gas which urges said accumulator and valve piston means against hydraulic fluid of said piston and accumulator regions and whereby said valve piston means is further urged by said accumulator pressure gas to seat against said annular valve seat surface thereby checking surrounding hydraulic fluid pressurized by said accumulator piston means in said accumulator region from flowing into said piston region, said valve piston means disposed to move away from its annular valve seat surface while a forming blow induces a pressure buildup in said piston region exceeding said accumulator gas pressure, whereby piston region fluid is permitted to flow into said surrounding accumulator hydraulic region displacing said accumulator piston means and whereby said secondary piston means is permitted to move into said secondary chamber means and said second tooling member motion is thereby sustained following a forming blow.
 21. The forming machine recited in claim 14 wherein said fluid control means comprising valve piston means having a valve face communicable with hydraulic fluid in said piston region, said valve piston means disposed having reciprocating motion which enables said valve face to move against an annular valve seat surface in the interior wall of said secondary chamber means and adapted thereby to isolate said piston region from a low pressure reservoir arranged with said secondary chamber means, valve control fluid confined by said valve piston means in said secondary chamber means and isolated from said piston region and said low pressure reservoir, said valve control fluid adapted to exert a force which holds said valve piston means seated against the force of piston region hydraulic pressure acting on said valve face whereby fluid delivered into said piston region in response to operator controlled signal is contained and directed by said valve piston means to move said second tooling member to forming position, said valve control fluid being controlled in such manner that the seating force exerted by said valve control fluid on said valve piston means decreases rapidly when a single forming blow is struck against said second tooling member whereby resulting secondary piston displacement into said piston region induces and is only resisted by decreased hydraulic pressure in said piston region necessary to overbalance said decreased valve control fluid force and thereby hold said valve piston means unseated permitting hydraulic fluid to displace past said valve seat surface from said piston region into said low pressure reservoir and whereby second tooling member motion following a forming blow, being resisted by reduced piston region pressure, continues and is sustained until halted by said secondary stopping means.
 22. The forming machine recited in claim 21 wherein secondary piston head means in rigid attachment to secondary piston shaft means within said secondary chamber means and disposed in sealed reciprocating contact with chamber cylinder means, said piston region confined in said secondary chamber means by the end face of said secondary piston head means, said secondary piston head means having a larger outside diameter than said secondary piston shaft means, chamber secondary pressure gas confined in said secondary chamber means and disposed communicable within said chamber cylinder means and around said secondary piston shaft means between the underhead surface of said secondary piston head means and said piston entrance means, said secondary pressure gas exerting a force on the underhead surface of said secondary piston head means which urges said secondary piston head and shaft means to displace into said piston region, said valve control fluid adapted to hold said valve piston means seated while hydraulic fluid is delivered into said piston region moving said secondary piston shaft means out from said secondary chamber means against the force of said secondary pressure gas on the underhead surface of said secondary piston head means and thereby moving said second tooling member to forming position, said valve control fluid controlled in such manner that the valve seating force exerted on said valve piston means rapidly decreases when a forming blow is struck whereby resulting secondary piston shaft displacement into said piston region induces reduced hydraulic pressure to unseat said valve piston means and whereby said reduced hydraulic pressure in said piston region produces a reversal of the net force of said secondary pressure gas and said piston region fluid acting on said secondary piston head means and whereby said net force following a forming blow urges said secondary piston shaft means into said secondary chamber means and thereby acts to sustain second tooling member motion induced by a forming blow until said motion is halted by said secondary stopping means.
 23. The forming machine recited in claim 14 wherein said fluid control means comprising valve piston means having a valve face communicable with hydraulic fluid in said piston region, said valve piston means disposed having reciprocating motion enabling said valve face to move against an annular valve seat surface in the interior wall of said secondary chamber means whereby a part of the area of said valve face is isolated from communication wIth said hydraulic fluid in said piston region, valve spring means disposed urging said valve piston means toward said valve seat surface, hydraulic venting means adapted to reduce the hydraulic pressure on said isolated valve face area while said valve piston means is seated, thereby reducing the force of piston region pressure acting to unseat said valve piston means to a level less than the force of said valve spring means and thereby enabling said valve spring means to maintain said valve piston means seated whereby fluid delivered into said piston region in response to operator controlled signal is contained and directed by said valve piston means to move said second tooling member to forming position, and whereby the impact of a forming blow causes hydraulic pressure in said piston region to increase to a level overbalancing the force of said valve spring means and thereby causes said valve piston means to unseat releasing said piston region fluid over the entire area of said valve face (ar5Z-ar5V) and whereby, continuing to overbalance the force of said valve spring means, said hydraulic pressure in said piston region drops as a result of the increase in valve face area over which said fluid is released to act and whereby said hydraulic fluid at reduced pressure displaces said valve piston means away from its valve seat surface as said secondary piston means displaces into said piston region following a forming blow and whereby second tooling member motion continues and is sustained following a forming blow until halted by said secondary stopping means.
 24. The forming machine recited in claim 23 wherein said valve spring means comprising valve spring pressure gas confined in said secondary chamber means and sealingly isolated from said piston region fluid by said valve piston means, said valve spring pressure gas confined in such manner as to act on said valve piston means over a pressure area (ar5X-ar5V) and thereby urge said valve piston means to reciprocate towards said valve seat surface.
 25. The forming machine recited in claim 23 wherein said secondary chamber means integrally connected with and contained in said second tooling member, said secondary piston means disposed on the far side of said second tooling member from said first tooling member and adapted having sealed reciprocating entry into said second tooling member on said far side and therein disposed confining said piston region, the portion of said secondary piston means disposed outside said second tooling member being secured with the machine foundation whereby secondary piston displacement into and out from said piston region results as said second tooling member moves in direction respectively away from and toward said first tooling member, said valve piston means being a ring shaped member disposed within said second tooling member surrounding the space into which said secondary piston means is received, said valve piston means disposed having reciprocating motion in the direction of said common axis and oriented to move in direction away from said first tooling member when closing against its vlave seat surface.
 26. The forming machine recited in claim 23 wherein secondary piston head means in rigid attachment to secondary piston shaft means within said secondary chamber means and disposed in sealed reciprocating contact within chamber cylinder means, said piston region confined in said secondary chamber means by the end face of said secondary piston head means, said secondary piston head means having a larger outside diameter than said secondary piston shaft means, secondary pressure gas confined in said secondary chamber means and disposed communicable within said means chamber cylinder and around said secondary piston shaft means between the underhead surface of said secondary piston head means and said piston entrance, said secondary pressure gas exeRting a force on the underhead surface of said secondary piston head means which urges said secondary piston head and shaft means to displace into said piston region, said valve spring means adapted with the aid of said hydraulic venting means to hold said valve piston means seated while hydraulic fluid is delivered into said piston region moving said secondary piston shaft means out from said secondary chamber means against the force of said secondary pressure gas on the underhead surface of said secondary piston head means and thereby moving said second tooling member to forming position, said valve piston means adapted to unseat when a forming blow induces a pressure increase in said piston region whereby piston region fluid is released over the entire area of said valve face (ar5Z-ar5V) which in turn results in a decrease in piston region hydraulic pressure producing a reversal of the net force of said secondary pressure gas and said piston region fluid acting on said secondary piston head means and whereby said net force following a forming blow urges said secondary piston shaft means into said secondary chamber means and thereby acts to sustain second tooling member motion induced by a forming blow until said motion is halted by said secondary stopping means.
 27. The forming machine recited in claim 26 wherein said valve spring means comprising valve spring pressure gas confined in said secondary chamber means and sealingly isolated from said piston region fluid by said valve piston means, said valve spring pressure gas confined in such manner as to act on said valve piston means over a pressure area (ar5X-ar5V) and thereby urge said valve piston means to reciprocate towards said valve seat surface, said valve spring pressure gas disposed connected in fluid communication through piping or other passage means with said secondary pressure gas acting on the underhead surface of said secondary piston head means, the area ratio of said underhead surface (ar5U-ar5T) to said end face surface (ar5U) of said secondary piston head means being less than the area ratio of said valve pressure area (ar5X-ar5V) acted upon by said valve spring gas to the area of said valve face (ar5W-ar5V) exposed to piston region fluid when said valve face is seated whereby said secondary pressure gas induces insufficient piston region hydraulic pressure to unseat said valve piston means before a forming blow, the area ratio of said underhead surface (ar5V-ar5T) to said end face surface (ar5U) of said secondary piston head means being greater than the area ratio of said valve pressure area (ar5X-ar5V) acted upon by said valve spring gas to the full area of said valve face (ar5Z-ar5V) whereby, once said valve piston means has unseated after a forming blow, the hydraulic pressure in said piston region necessary to continue displacement of said valve piston means away from its seat produces a force on the end face of said secondary piston head means which is less than the force exerted by said secondary pressure gas on said underhead surface thereby producing a net force urging said secondary piston means into said secondary chamber means and sustaining second tooling member motion induced by a forming blow until said motion is halted by said secondary stopping means. 